diff --git a/cpp/includes/Example.hpp b/cpp/includes/Example.hpp
index b80c8cf..c76cdf2 100644
--- a/cpp/includes/Example.hpp
+++ b/cpp/includes/Example.hpp
@@ -4,7 +4,7 @@
 #include <iostream>
 
 class Example {
-  friend std::ostream &operator<<(std::ostream &out, const Example &data);
+  friend std::ostream &operator<<(std::ostream &, const Example &);
 
 public:
   Example();          // constructor